Search results for "Titan"
showing 10 items of 1109 documents
Specifics of polarisation switching in PbNi1/3Nb2/3O3–PbTiO3–PbZrO3 ferroelectric ceramics
2004
Abstract The growing interest in disordered relaxor ferroelectrics is due to unusual properties mainly related to the existence of broad phase transitions characteristic to the systems. The effects of bias field on the dielectric response and polarisation switching are studied in the 0.5 PbNi 1/3 Nb 2/3 O 3 – x PbTiO 3 –(0.5− x ) PbZrO 3 system at different PbTiO 3 :PbZrO 3 ratio. Thermal behaviour of normalised remnant polarisation P r / P max of compositions with content of lead titanate x =0.33 and x =0.35 at frequency 0.1 Hz and different values of field E o are measured. Results of measured polarisation and depolarisation currents are compared with characteristics of polarisation switc…
Influence on the phase transitions of barium titanate of the manganese valency, introduced as a substituant in the titanium site
1991
Abstract A small amount of manganese introduced in BaTiO3 modifies strongly the vibrational and electronic properties of the pure compound. Dielectric response and EPR measurements are reported in order to study the influence of the manganese valency on the ferroelectric-paraelectric phase transition.
Thermodynamic considerations of the grain size dependency of material properties
1994
Phase transitions which depend on grain size induce very interesting properties in materials such as zirconia or barium titanate. A new and rigorous thermodynamic treatment of this type of phase transition is proposed with consideration of the surface phenomena. An interpretation is given of the observed differences when the material—particularly BaTiO3—under consideration is a fine grain powder or is a fine grain ceramic.
Synthesis and Characterization of Lead-Free (1-x)(K0.5Na0.5)Nb1-ySbyO3-xBaTiO3
2011
In this study lead-free ceramics with a formula (1-x)(K0.5Na0.5)Nb1-ySbyO3-xBaTiO3 have been synthesized and studied. XRD studies showed that all compositions have perovskite structure with monoclinic or tetragonal cell depending on substitution level. KNN ceramics with BaTiO3 have more homogeneous structure and increased density in comparison with pure KNN or antimony substituted KNN. Dielectric measurements revealed diffuse phase transition.
Polar nanodomains and local ferroelectric phenomena in relaxor lead lanthanum zirconate titanate ceramics
2005
Transparent Pb0.9125La0.0975(Zr0.65Ti0.35)0.976O3 ceramics (conventionally abbreviated as PLZT 9.75/65/35) is a typical relaxor characterized by the absence of the ferroelectric order at the macroscopic scale. In this letter, we report on the observation of complex polar structures on the surface of this material via piezoresponse force microscopy (PFM). The irregular polarization patterns are associated with the formation of a glassy state, where random electric fields destroy the long-range ferroelectric order. The measure of the disorder, the correlation length of ∼50nm, was directly deduced from the PFM images. Local poling of relaxor ceramics resulted in the formation of a stable micro…
Low temperature structural transformations on the (001) surface of SrTiO 3 single crystals
2020
This work was supported by the Ministry of Education and Science of Ukraine under the contract M/51–2019 within the framework of the Program of Ukrainian–Latvian Scientific and Technical Cooperation and Latvian–Ukranian Grant LV-UA/2018/2. Authors are indebted to L.L. Rusevich, G. Zvejnieks, V.P. Gnezdilov and A. Glamazda for stimulating discussions.
Preparazione e caratterizzazione di fotocatalizzatori a base di TiO2
2011
Photocatalytic solar light H2 production by aqueous glucose reforming
2018
A series of tungsten and nitrogen doped Pt-TiO2 samples were prepared with the aim to extend the TiO2 absorption to the visible light region and to enhance the separation efficiency of the photogenerated electron/hole pairs. The physicochemical features of the powders were characterized by Xray diffraction (XRD), UV/Vis reflectance spectra, specific surface area (SSA) determinations, and transmission electron microscopy (TEM) analyses. The influence of the presence of different doping agents was evaluated, under anaerobic conditions, in the aqueous photo-reforming of glucose to form H2 at ambient pressure and temperature under a halogen lamp or natural solar light irradiation. Arabinose, er…
TiO2-CeO2 based catalysts for photocatalytic oxidation of VOC and water splitting reactions
2016
Photocatalysis with TiO2 is one of the most promising green process for the decomposition of organic pollutants and the hydrogen production . Photo-oxidation of 2-propanol, representative of volatile organic compounds (VOC) and photo-catalytic water splitting for H2 production were investigated over TiO2 catalysts doped with a metal (Au and Ag at 1wt. %) and/or ceria (10 wt.%).